Thermal_Energy_and_Friction-1

docx

School

University of Cincinnati, Main Campus *

*We aren’t endorsed by this school

Course

1005C

Subject

Mechanical Engineering

Date

Dec 6, 2023

Type

docx

Pages

Uploaded by BaronDangerTapir33

Thermal Energy and Friction Date Name Page 1 of 7 10/12/23 Payton Hasty

Introduction The mechanical energy of a mass is the sum of the kinetic energy that the mass has because of its motion, and the potential energy it has because of its location. When friction acts on a mass, the friction takes away mechanical energy. We can imagine that the energy is still there - in the motion of the atoms of the environment and the mass itself. But this energy is no longer readily available to do work. We can only detect this energy by a rise in temperature. That is why the energy friction "steals" is often called thermal energy . In this lab you will look at a simulated motion - a ball rolling on a parabolic track. You will investigate how much thermal energy is removed by friction as the ball rolls on the track. Required Materials Energy Skate Park: Basics Procedure Go to the simulation by clicking on the link: Energy Skate Park: Basics . If the link does not work, copy and paste the following address into a browser: https://phet.colorado.edu/en/simulation/energy-skate-park-basics Click on the arrow in the gray circle to launch the simulation. Click twice on the middle simulation Friction . Page 2 of 7

Note the controls on the bottom: You can have normal or slow motion. You can pause (and start) the motion. You can go forward in discrete steps. You can reset to the initial conditions. Page 3 of 7

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version

Access to all documents
Unlimited textbook solutions
24/7 expert homework help

Now check the box for Grid and move the slider for Friction all the way to None. Even though the simulation shows a skate boarder, the mass is really just the red ball. The skate boarder just makes it look more interesting. You need to focus on the red ball. Now drag the skate boarder to the top of the track (either side) and release. Page 4 of 7

Notice that the ball always returns to the same place it started after one cycle (back and forth). No friction means no mechanical energy is lost. The mechanical energy just cycles between potential and kinetic. Record the mechanical energy of the ball at the highest point - where it is all potential. Use mgh. Assume that m is 40 kg. Use the grid to find h in meters. Record your result in the table below as Starting Mechanical Energy . Motion with Friction Move the friction slider to the middle and start the motion again. Let the ball go through one cycle and stop it when it is at its highest point. Notice that this is lower than the starting point since mechanical energy is lost to friction. Calculate the potential energy at this point and record your result as First Cycle Mechanical Energy . Repeat this for a Second Cycle, Third Cycle and Fourth Cycle . Page 5 of 7

Mechanical Energy Thermal Energy Starting 2354 J First 981 J 1373 J Second 549 J 432 J Third 353 J 196 J Fourth 196 J 157 J Find the Thermal Energy for the first cycle by subtracting the mechanical energy at the end of the first cycle from the starting mechanical energy. Record the result in the first unshaded cell under Thermal Energy. The Thermal Energy at the end of the second cycle is the mechanical energy at the end of the first minus the mechanical energy at the end of the second. Repeat this for all four values of the Thermal Energy. Is the amount of Thermal Energy lost on each cycle the same? Comment in some detail on the pattern you got. Explain why this pattern might make sense given what you know about the motion. Page 6 of 7 No, the amount of thermal energy lost in each cycle is not the same. The loss of energy is not the same because of the frictional force between the skateboard, or the ball, and the surface it is on. As it moves down the ramp and back up, the friction that is generated is the cause of losing the amount of energy. The path that the ball or skateboarder takes decides how much energy is lost. So with each movement the ball or the skateboarder moves the more energy is lost. So, the loss of energy is not the same each time because the distance traveled is different each time.

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version

Access to all documents
Unlimited textbook solutions
24/7 expert homework help

Now set the Friction slider about one-quarter of the way from None. Now repeat the entire experiment with this setting. Mechanical Energy Thermal Energy Starting 1766 J First 1570 J 196 J Second 1373 J 197 J Third 1172 J 201 J Fourth 981 J 191 J Is the amount of Thermal Energy lost on each cycle the same? Comment in some detail on the pattern you got. Explain why this pattern might make sense given what you know about the motion. Page 7 of 7 The amount of thermal energy lost on each cycle is not the same. The pattern I got shows that in the first cycle 196J are lost. In the second cycle, the thermal energy increases very little, only 1J. In the third the increase is 4J and in the fourth there is a decrease of 10J. This pattern suggests the thermal energy loss is not the same and it changes when the mechanical energy changes so does the thermal energy. The variation in the loss of thermal energy reflects that the system’s motion and the force of friction are not perfectly consistent.